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Discussion Starter #1 (Edited)
HERE IS A QUICK STORY, MY CAR WAS RUNNING TERRIBLE, HESTITATION, STUMBLING, THEN THE CEL CAME ON I SCANNED IT AND THIS IS WHAT IT SAID...
P0171 System Too Lean (Bank 1)
DTC for which Freeze Frame was Stored P0171
Fuel System 1 Status Closed Loop
Fuel System 2 Status Not Supported
Calculated LOAD Value 36.08 %
Engine Coolant Temp 204.80 °F
Short Term Fuel Trim - Bank 1 42.19 %
Long Term Fuel Trim - Bank 1 25.00 %
Short Term Fuel Trim - Bank 2 0.78 %
Long Term Fuel Trim - Bank 2 -10.94 %
Engine RPM 746 rpm
Vehicle Speed Sensor 0.00 mph

I CLEANED THE MAF WITH ELECTRICAL CLEANER AND RESET THE PCM BY PULLING THE #15 FUSE.

IT RAN OK FOR A LITTLE BIT, FEW HOURS THEN I GET A P1131.

WHAT COULD BE CAUSING THIS?

I READ SOME ON HERE, COULD IT BE AS SIMPLE AS AN O2 SENSOR??

THANKS FOR YOUR HELP

JONRANK
 

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Discussion Starter #3 (Edited)
Master, Could You Elaborate On That A Little Further. What Is The Dpfe Sensor? Where Is The Major Culprit In The Evap System?

Should I just pull down the passenger-side fender lining and look at the lines going to the canister?

I went outside and looked at the rubber hoses in the system (I read a couple of master's previous posts). All the rubber hoses that I looked at tonight looked for the most part okay. But perhaps , well highly likely, totally unrelated...I saw that this wire's insulation had been "rubbed" off, Is this of any significance? I will still fix it for the heck of it though.
 

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Discussion Starter #4
Any Help?
 

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Yes you need to look at all the lines going from the engine up to the passenger side front of the car to the EVAP canister. Also, check all other vacuum lines including the green and red plastic ones and the hoses that connect the valve cover breather to the air intake tube and the PCV valve. These hoses dry-rot and crack with age, and if you don't know if they've been replaced chances are they haven't. It's very inexpensive to do so.

The DPFE (differential pressure feedback EGR) sensor is located at the back of the engine and has 2 rubber hoses going from it to the EGR pipe that connects the EGR valve to the exhaust manifold. But you shouldn't be looking at the EGR at this point.

And that wire in the picture is a ground for the temp gauge. It's not going to be a contributor to any of your problems.
 

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Discussion Starter #6
I Was Out At The Car Looking Everywhere For Vacuum Leaks And I Noticed That The Plug Where The 2 Red Lines Plug Into The Throttle Body Was Hanging Halfway On. I Pushed It All The Was Back On. Car Cleared Up (i Think)! So Far Its Running Wonderfully And Smoother Than It Has Been In Quite Some Time. Thanks Chris For The Help.

I Do Realize That With Writing This That I Have Indeed Jinxed Myself And Will Have The Same Codes Tomorrow!!

Still...thanks

Jonfrank
 

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Discussion Starter #7 (Edited)
Ok, So I Am Still Getting The P1131 Code And The Car Is Getting Terrible Terrible Gas Mileage.

So I Pop The Hood To Check Lines Again And I Reach Up And Check The Green Vacuum Line And It Snaps In 2 Right At The "saucer" Shaped Sensor (what Is Its Name?).

Where Do I Buy The Red And Green Lines? Do I Go To The Junkyard?

Do I Need To Replace Anything Else?

When I Go To The Parts Store Or Junkyard Which Ever One Yall Tell Me I Will Have To Drive The Bird. Is That Safe? Its Running Exactly How It Was Before I Broke The Line...terrible!!

Please Give Me Feedback.

Thanks In Advance,
Jonfrank
 

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Discussion Starter #9 (Edited)
I went to the Zone just a minute ago and just spliced a hose back to the egr from the green line...i reset the code and drove around a bit, surprisingly <sarcasm> the code came back. here is what it read. nothing much different.

Do the fuel trims look good?

How do I replace the red and green lines completely with rubber hose?? Do I splice 90's to plug into the egr? what about the 2 reds that join together?

Pending:
P1131 Lack Of HO2S11 Switches - Sensor Indicates Lean

MIL OFF
MisFire Monitor Complete
Fuel System Monitor Complete
Comprehensive Component Monitor Complete
Catalyst Monitor Not Complete
Heated Catalyst Monitor Not Supported
Evaporative System Monitor Not Supported
Secondary Air System Monitor Not Supported
A/C System Refrigerant Monitor Not Supported
Oxygen Sensor Monitor Complete
Oxygen Sensor Heater Monitor Complete
EGR System Monitor Not Complete

DTC for which Freeze Frame was Stored P1131
Fuel System 1 Status Closed Loop
Fuel System 2 Status Not Supported
Calculated LOAD Value 63.53 %
Engine Coolant Temp 206.60 °F
Short Term Fuel Trim - Bank 1 42.19 %
Long Term Fuel Trim - Bank 1 4.69 %
Short Term Fuel Trim - Bank 2 -4.69 %
Long Term Fuel Trim - Bank 2 -7.03 %

Engine RPM 2193 rpm
Vehicle Speed Sensor 73.32 mph
 

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Discussion Starter #10
Validity?

IM HUNTING WITH THIS! DOES THIS WORK ON OUR CARS TO ELIMINATE THE MAF FROM THE EQUATION?

To confirm this disconnect the MAF sensor connector. This puts the vehicle into Failure Mode and Effects Management (FMEM). In FMEM mode, airflow is inferred by using rpm and throttle position instead of reading the MAF sensor. (In addition, the BARO value is reset to a base/unlearned value.) If the lean driveability symptoms go away, the MAF sensor is probably contaminated and should be replaced. If the lean driveability symptoms do not go away the MAF sensor is probably not contaminated.
 

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The "saucer" thing isn't a sensor, it's the EGR valve. The red/green vacuum lines aren't available for purchase new. You either have to go the junkyard route or just use replacement rubber vacuum line. There is some validity in disconnecting the MAF to diagnose problems. Your short term fuel trim on Bank 1 (passenger side) isn't normal. Ideally you want it as close to 0 as possible. Positive means it's adding fuel and negative means its subtracting, so it's reading quite lean on that one side, which follows from it setting the codes. You may have an intake manifold gasket leak on the passenger side or maybe a leaking injector O-ring.
 

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Discussion Starter #12
Master486, whomever will listen,

I replaced the vacuum lines, checked everywhere for leaks, nothing. Car still throws the p1131 code fairly immediately. Im trying to piece things together so...getting at best 22mpg highway, car running worse after it is warm, the exhaust having a strong smell...would it be the O2 sensor? Im pretty sure the 2 fronts are bosch sensors. Should I replace the pass. side O2 sensor? Where do I get them the cheapest? rockauto or I noticed a couple of guys some form Summit.

Do y'all condone this move?

Thanks
JonFrank
 

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keep checking for more vacuum leaks. listen for whistling with the hood popped. make sure the violin case isn't cracked, and the hose clamps and boots are tight and in good shape. check around the throttle body on the passenger side, there is a rubber vaccum T thaere that seems to like to develop a leak on our cars.
 

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keep checking for more vacuum leaks. listen for whistling with the hood popped. make sure the violin case isn't cracked, and the hose clamps and boots are tight and in good shape. check around the throttle body on the passenger side, there is a rubber vaccum T thaere that seems to like to develop a leak on our cars.
You're talking about a 94/95 intake setup, which this poster does not have.

Replacing an oxygen sensor isn't likely going to help anything. The code is indicating that the computer is at it's limit in correcting for an overly lean condition. If the sensor were stuck reading lean, it would likely throw the appropriate code for the sensor not switching properly. You should check everything fuel and air related to the passenger side including the fuel pressure and regulator, injectors, and check for air leaks. At this point you'd easier locate a leak using propane, especially if it's an intake or injector O-ring that's leaking.
 

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Discussion Starter #15 (Edited)
I have been driving the car for a week now, it was running really well and now today i get
P1131
P0131
and two pending P1131 and P0131.

I did my reading on here and of course the thread that I was really interested in ends abruptly without resolution.

Last weekend i went to the junkyard and bought the EVAP sensors behind the bumper, I haven't replaced them yet.

Should I go ahead and replace them?

Does the new P0131 code point towards O2 sensor?

I have a newer set of plug wires, should I replace them?

I kinda need to know where to go with this, Ill replace all of the above if need be.

Ideas? Advice?

One more thing, I heard rumor that our birdies will not necessarily throw a a CEL. IS this true?
Thanks in advance guys.
JonFrank
 

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First off, why did you buy the EVAP stuff? There was no reason based on the information you provided that would prompt a reason to change any of the electronics related to the EVAP system.

P1131 is the same story as above. The computer has reached it's limit in adding fuel to the passenger side of the engine, so there is either not enough fuel or too much air on that side.

P0131 is a totally different code and a different oxygen sensor than the original codes. It's the same side of the engine (Bank 1, passenger side), but now it's the rear sensor. The code indicates low sensor voltage. This could now be a sensor problem or wiring, but it could also be a false code triggered by your other problems.

Have you yet done anything to make sure that you don't have a vacuum leak? Only 1 side of the engine is being affected here, so you need to check the intake manifold and injector O-rings like I stated above. Also, you need to check the injectors themselves because you might have one that is not firing, clogged, or sticking. You can check them by feeling them to make sure they click or you can hold up a screwdriver against them and listen that way.

And yes, there are certain problems that won't trigger a CEL.
 

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Discussion Starter #17 (Edited)
I did check everything, I haven't done anything because it ran well for the week.

Yeah I bought EVAP stuff cause I got an EVAP code late last weekend and I went to the yard looking for the Vacuum lines I busted..and I was there and they were cheap.

Master I have looked everywhere for leaks, I know you don't condone it but I used carb cleaner to look for leaks (I had nothing else)...found nothing.

I wasn't really sure how to check for a bad injector, But now that I do I will check them on the passenger side. A couple months ago I had a couple issues with the injector at cylinder 4, but it threw misfire codes.

UPDATE: I CHECKED THE INJECTORS, THEY ARE ALL CLICKING AWAY!! NEXT??

Thanks for being persistent.
 

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i know its a lot of work, but take out the oxygen sensors before the catalytic convertes....put the one that was on the passenger side to the drivers side, and vice versa.....if the oxygen sensor is the problem, the code will change to a different one indicating that bank2 is now an issue.......if the code stays on bank1, then its not the O2, and it is indeed something upstream of oxygen sensor..........done any exhaust work?? an exhaust leak will wreak havoc with the adaptive fueling strategy of the computer
 

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Discussion Starter #19
I had to put new mufflers on a few months back but they are in the factory spot so nothing near the system.

Maestro I will check that next weekend when I drive home, I'd rather put it on my dads lift than crawl in the dirt!!

BUT WHAT ABOUT THIS:
I said that the car ran just fine during the week, which was after a full tank of gas. At about half a tank is when the car was running really bad and started throwing codes. After realizing that I filled the car up yesterday. I drove it this morning ~50 miles. Car is running fine, no codes.

Could the pump be on the fritz and perhaps the sock is clogged?

This has to be more than a coincidence.

Thanks
 

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I had to put new mufflers on a few months back but they are in the factory spot so nothing near the system.

Maestro I will check that next weekend when I drive home, I'd rather put it on my dads lift than crawl in the dirt!!

BUT WHAT ABOUT THIS:
I said that the car ran just fine during the week, which was after a full tank of gas. At about half a tank is when the car was running really bad and started throwing codes. After realizing that I filled the car up yesterday. I drove it this morning ~50 miles. Car is running fine, no codes.

Could the pump be on the fritz and perhaps the sock is clogged?

This has to be more than a coincidence.

Thanks
when was the inline fuel filter changed last?
 
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